1. Field of the Invention
This invention relates in general, to 3-dimensional rearrangement puzzles and in particular, to three-dimensional rearrangement puzzles which hold together.
2. Description of the Prior Art
The following list comprises those patent documents of which I am aware which are closest to the present puzzle: Hungarian No. 170062, Rubik; Japenese Nos. 55-8192, 55-3956 and 55-8193, Ishige.
Rubik has disclosed a puzzle based on the shape of a cube. Although the outward appearance of Rubik's puzzle may take many forms, the organization of the parts is that of a cube subdivided into 27 little cubes which are stacked in rows, columns, and layers in a 3.times.3.times.3 pattern. Rubik has also disclosed a puzzle whose parts are organized by a cube subdivided into 8 little cubes which are stacked in rows, columns, and layers in a 2.times.2.times.2 pattern. In each of these puzzles the parts comprising any face of the large organizing cube may be rotated by 90.degree., 180.degree., and 270.degree. and so, bring all the parts into a new configuration essentially the same as the original configuration. The parts hold each other together by a series of axles, extensions and channels.
Ishige has disclosed in his three patent documents, puzzles very similar to the two puzzles Rubik has disclosed, but with alternate patterns of extensions and channels to hold the parts together. In Douglas Hofstadter's Scientific American article (March 1981, page 39) and in David Singmaster's Notes On Rubik's "Magic Cube", two other similar puzzles are said to be under development. These two puzzles are described as being based on rectangular parallelepipeds which are subdivided into little cubes which are stacked in rows, columns, and layers in a 2.times.3.times.3 pattern for one puzzle and in a 4.times.4.times.4 pattern for the other puzzle.
Each of these prior art puzzles differs from each of the present puzzles in each of the following ways.
1. Each is organized by the shape of a rectangular parallelepiped.
2. Each is subdivided by three systems of parallel planes, one system parallel to each pair of parallel faces of said rectangular parallelpiped
3. The component parts are stacked in rows, columns, and layers.
4. The allowed rotations, those which bring the parts into a new configuration essentially the same as the original configuration, are each either 90.degree., 180.degree., or 270.degree. rotations.
5. Each face has the 180.degree. rotation as an allowed rotation.
6. The axes about which the allowed rotations may be performed are mutually perpendicular.
7. There are exactly 3 such axes.
8. Each of these prior art puzzles has a spatial organization of its parts into blocks which may be rotated with respect to those parts not in the block, and this spatial organization is different from the spatial organization of each of the present puzzles.
9. Both the prior art puzzles and the present puzzles have rearrangement problems, a rearrangement problem being the problem of restoring the parts to their exact original positions after they have been permuted in an arbitrary manner. The rearrangement problem posed by each of the prior art puzzles is essentially different from the rearrangement problem posed by each of the present puzzles.